Method and apparatus for manufacturing artificial silk



June 23, 1936.

METHOD AND APPARA F. W. MATTlNSON TUS FOR MANUFACTURING ARTIFICIAL SILK Filed Jan. 14, 1952 6 Sheets-Sheet 1 lNVENTOl-k June 23, 1936. F. w. MATTINSON METHOD AND APPARATUS FOR MANUFACTURING ARTIFICIAL SILK Filed Jan. 14, 1952 6 Sheets-Sheet ilk 7 BY INVENTOR zifii ifrzdllallmsm ATTO R N EYS June 23, 1936. F. w. MATTINSON 2,045,530

METHOD AND APPARATUS FOR MANUFACTURING ARTIFICIAL SILK I Filed Jari. 14, 1952 6 Sheets-Sheet s INVENTOR I midi WW/mfla/fihsa/z ATTORNEY June 23, 1936. F. w. MATTINSON METHOD AND APPARATUS FOR MANUFACTURING ARTIFIC IAL SILK Filed Jan. 14, 1932 6 Sheets-Sheet 4 ATTORN EYS- June 23,. 1936. F. w. MATTINSON 2,045,530

METHOD AND APPARATUS FbR MANUFACTURING ARTIFiCIAL SILK- Fil'ed Jan. 14, 19:52 A 6 Sheets-Sheet 5 INVENTOR Frail/f fl ifrmfla/lz/wam BY $7M /5l/l/ F M.

ATTORNEY June 23, 1936. F. w, MATTINSON METHOD AND APPARATUS FOR MANUFACTURING ARTIFICIAL SILK 6 Sheets-Sheet 6 Filed Jan II l "W mi R O T N E V m ATTORNEYS Patented June 23, 1936 Frank waned Mattinson, Utica, N. Y., assignor to Skenandoa Rayon Corporation,

corporation of Delaware Utica, N. Y., a

Application January 14, 1932, Serial No. 586,553

21 Claims.

This invention relates to the manufacture of artificial silk, and more particularly to a novel method of manufacturing artificial silk or rayon thread having more uniform dyeing qualities, or dye afiinity as it is sometimes called, than has heretofore been possible.

A major difficulty which has been encountered for many years in the manufacture of rayon thread or yarn has been that the finished thread cannot be made so as to have uniform dyeing qualities. Some yarn is more absorptive of dye than others," and even yarn from different parts of thesame yarn cake varies in dye amnity. This necessarily results in undesirable variations in color or shade of the dyed thread, or of fabric produced therefrom. Many and repeated efforts have been made in the industry to overcomethis trouble, but so far as I- know, no successful or practical way of doing so has been found prior to my present invention.

I shall describe my invention more particularlywith reference to the cake" or centrifugal spinning bucket method of spinning rayon from viscose, that being the industrial process to which I have applied'my invention. It may-be, however, that in proper cases my invention iscapable of advantageous application to other processes of manufacturing artificial silk. I

I have discovered by extended investigation and test that in manufacturing rayon thread or yarn from viscose by the centrifugal spinning bucket method of spinning, the principal cause of nonuniform dye afiinity of the spun yarn is the variation in the tension applied to the yarn during spinning, .due to decrease of centrifugal force as the yarn cake builds inwardly from the wallof the centrifugal spinning bucket (sometimes called the. spinning pot) toward the axis of the bucket. Bylong andcareful observation, I have found that the thread on the outside of a spunyarn cake, spun by this centrifugal spinning method, is sufiiciently different in structure from the thread on the inside of the completed cake so that when the whole yarn cake is; dyed the thread on the outside'of .the cake'absorbs a less amount of dye and'comes out a different shade, of color. I have discovered'that the more the yarn is stretched during its" manufacture the less will be 'its dye absorption, and consequently yarn from the outside of a spun cakedyes'to a lighter shade-than does yarn from the inside of the same cake.

Having discovered that the foregoing is a principal cause of the non-uniform dyeing qualities which'have heretofore characterized substantially all viscose rayon made by the centrifugal spinning method; to the. great detriment of the commercial value of theyam, I have invented a method of overcoming this difficulty. Broadly stated, this method consistsin making a progressive compensating adjustment or regulation, during the operation of spinning each yarn cake,

which so controls the actual structure of the yarn, or the individual filaments of which it is composed, that it produces compensation for the non-uniform dyeing qualities which would otherwise result. I have thus succeeded in producing a spun yarn -cake in which yarn or thread in all parts of the cake has substantially uniform dyeadjustment or regulation can be effected during the spinning operation. By spinning operation? .in that sense I refer broadly to all the various operations which take place between the squirting of viscose filaments through the spinnerette .into the spinningbath" and the time the spun cake is finally .doifed"fro'm the spinning pot.

From a practical commercial standpoint, the

method which I now prefer for producing the required regulation of the yarn structure, which method I shall presently describe in greater detail in connection with the accompanying drawings, consists in applying a progressively increasing tension to the thread or yarn as it comes out of the spinning bath and moves" towards the godet wheel. This incre'asing tension is so regulated that it produces a compensating change in the final. structure of the thread, or the individual filaments'thereof, which neutralizes the effect of the decreasing centrifugal pull exerted on the thread during the spinning of each yarn cake, due to the decreasing inside radius of the yarn cake as it builds inwardly from the wall of whatl now consider the preferred form of myin- .-vention, this decreasing centrifugal pull "on 1 the ,thread is neutralized or compensated by the 111- trolling the thread structure to impart uniform dyeing qualities to the yarn.

Another way in which I have found. that the desired compensation can be introduced duri the spinning operation, to control the yarn structure, is gradually to increase the speed of rotation of the spinning pot during the spinning of each cake ,in sufiioient amount to offset the .de-, creasing weight of the thread due to its lessen ing free length and the decreasing centrifugal force due to the diminishing inside radius of the cake. In this case, the number of revolutions per second of the spinning pot being increased, it is desirable, also, in order to prevent increased twist of the thread, to make corresponding adjustments of the speed of other parts of the apparatus, to keep their relation uniform. Thus the 'godet speed should be increased in relation to the pot speed in order to maintain uniform twist; the speed of the viscose pump should be increased to maintain uniform denier; and the distance that the thread is immersed in the spinning bath should be increased in order to compensate for the increased speed of the yarn.

Still another way in which the desired control of the yarn structure can be accomplished .to

introduce the compensation necessary to produce uniform dyeing quality, is gradually to increase ;the length of time that'the' thread is immersed in the spinning (coagulating) bath after it emerges from the spinnerette. This, I have found, changes the structure of the individual .filamen'ts of the thread (yarn) in such a way that the thread tends to dye lighter in color as the time 'of immersion in the spinning bath is increased, thus neutralizing the increasing dye afiinity due the diminishing centrifugal pull during the spinning of each cake, that would otherwise cause the thread on the inside of the yarn caketo absorb more dye than the thread on the outside.

- What I now consider to be .the preferred commercial form of apparatus for carrying out my method is one-whichoperates by control of the thread tension in the manner first described. I

shall accordingly describe that form of apparatus, and how my method is performed by use of the same, in greater detail in connection with theaccompanying drawings, in which:

Figure 1 is a plan view of an artificial silk spinning apparatus embodying the invention;

Fig. 2 is a vertical elevation of the same, partly in section, and partly broken away;

Fig. 3 is a detailed view of a part of Fig. 2; 'Figs. 4, 5, 6, 7 and 8 show details of mechanism for operating the variable tension guides. Fig. 4 is -a plan view of this mechanism. Fig. 5 is a vertical section on line 55 of Fig. 4. Fig. 6 is a transverse section on line 8-6 of Fig. 5. Fig. 7 is a horizontal section on line 1-1 of Fig.

. 5. Fig. 8 is a diagrammatic plan view illustrating in detail the motion of a part of the mecha- Fig. 9 is a detailed elevation, partly in section,

of an apparatus. for carryingoutthe method of the invention byprogressively increasing the,

tax

right-hand spinning unit by way of example, the others being similar, the viscose enters through the pipe and flows to the spinnerette I2 from whichit is ejected into the spinning bath Il in the form of a plurality of filaments shown at .Ii. 5 These filaments then pass over the fixed or sickle guide I4, then under the movable tension guide l5, whichis carried and operated by the longitudinally movable bar I6, in the manner explained hereafter. The filaments pass next 10 around the godet wheel orroller I1, and then pass down through the vertically reciprocating funnel guide I8, whence by the action of the rapidly rotating spinning pot or fbucket ID the filaments are spun-4. ,e. twisted--into yam-or thread, which by virtue of the centrifugal force exerted by the rapidly-rotating spinning bucket, winds up against-the inside of the spinning bucket or potfl't'o forma yarn cake", 20.

By more .particular'referenoe to Fig. 3 it will be seen that during the spinning of the yarn cake 20 the distance between the lower end I8a of the reciprocating funnel guide I8 and the point 200 where the yarn is actually wound into the yarn cake decreases during the spinning of each yarn cake, due to the fact that the cake builds inwardly from the wallof the spinning pot 18 toward the funnel guide, which is at the axis of the pot. Thecentrifugal force to which the filaments are subjected while they are being spun 8.0 is consequently progressively reduced during the spinning of each yarn cake, due not only to the decreasing radius, causing decreasing centrifugal force, but also because the length, and consequently the" weight, of the free yarn between the points Ila and 20a is continuously diminished.

To compensate for the progressively lessened tension applied-to the yarn during. the spinning of each cake, .due to these factors, I arrange the variable tension guide in the'manner already de- 40 scribed, and as shown in greater detail in Fig. 3.

At the beginning of the spinning operation the bar r it with its movable tension guides I5of which I shall now refer more particularly to the one shown in detail in Fig. 3-is adjusted by means of a hand wheel (shown in Figs. 1, 4 and 5) so that the movable guide-occupies the position I6 is automatically moved to the right, by the mechanism provided for that purpose and to be described presently, bringing the movable guide from the position shown at l5 to that shown at 15. This causes a progressive increase in the tension applied to the filaments I3, both because thetravel is longer and because a sharper angle is introduced therein. The distance between the positions i5 and I5, and the rate of motion, are so co-related with the rate of spinning that the increased tension produced by the movement of the guide It and bar It from their starting to their final position lust. compensates for the decreased tension due'to the lessening centrifugal force exerted by the spinning pot as the cake builds inwardly, decreasing'its radius. In this way a uniform tension and thread structure is maintained, and the. resulting yarn'has substan- 52a, between which-uslocated?apivotedapparat-v tially uniform dyeing properties.

Referring now more particularly to Figs. 4, 5', 6, 7 and 8, Fig. '4 shows a plan view of the 'mech anism for operating the movable 'bar IS in the manner just described. 2| is a pulley adapted to be driven by a belt 22, from a suitable source of power, as shown at the lower right hand side of Fig. 2. The pulley 2| is mounted on a shaft 23 which operates a speed reduction gear box 24. The reduced speed gear 25 drives a train of gears 26, 21, 28 (see Fig. 6). The gears 26 and 21 are the full lines in Fig. 8. The operation 'of the cam,

carried on a common stud 29, adjustably mounted on a bracket 30 to allow for taking up any possible play, and to give an accurate mesh of the gears. Gear 28 is keyed at-28a to the main spindle 3| (see Fig. 5). The spindle 3| is thread ed, and has mounted thereon an internally threaded sleeve 32, formed integrally with the bracket 32a on which is mounted the cam supporting frame 33. Frame 33 is provided at each side with a laterally extending guide rod 34, sliding .in the bearings 35 of the main'supporting frame or housing 36, so that as the spindle 3| is rotated, the cam frame 33 is moved parallel thereto on the guide rods 34. The main spindle shaft 3| is journaled in suitable bearings 31 in the same main supporting frame 36. Secured to the top of the cam frame 33 is a slotted cam plate 38 provided with a diagonally extending slot 39 (see Fig. 7). Within the slot 39 is arranged a cam roller 40 carrying a stud 4| which is secured to a sliding member 42 arranged to slide in a. direction transverse to that of the motion of the cam plate 38. Thistransverse sliding member 42 slides in a fixed guiding block 43 (see Fig. 5) integral with the cover 44 of the main supporting frame 36. This transverse sliding member 42 is connected by a suitable linkage 41 (see Fig. 8) to the movable bar l6, shown in Figs. 1, 2 and 3.

The operation of the mechanism is that as the pulley 2| is driven, the gear train 26. 21, and 28 is driven through the gearbox 24, and rotates the main spindle 3|. By 'virtue of its threaded engagement with the sleeve 32 this rotation of the spindle 3| moves the-entire cam assembly, including bracket 32a, cam frame 33, guide rods 34, and cam plate 38, from its left-hand position, shown in Fig. 5, toward the right, as shown by plate 38 is then to force the cam roller 40 backwardly, drawing with it the transversely sliding member 42 and thus'operating the movable bar l6 in the manner described. In Fig. 8 the initial position of the cam plate and roller is shown indotted lines and the final position, with the bar |6 retracted, is shown in the full lines. 4 f

' In order to stop the operation of the drive mechanism when the cam has reached the limit of-its travel, an automatic clutch 45-is provided as shown in detail in Fig.5. This clutch is gen- 'erally designated as 45, and consists of two members'46 and 41'. Clutch member 46 is integral wlth'the gear and is the drive member of the "clutch. Clutch member 41' is slidable on the reduced portion 3|a. of the'spindle 3|, and is normally kept in engagement 'withthe driving =i'nember 46 by means of the spring 48. "member 49 engages the collar portion of clutch Fork member 41',--'as shown in Fig. 5, and is pinned to- ..the shaft"50, whichis slidablyjournaled in bearings 5| on the main-'-frame.; 36: The shaft 50has mounted on its other end a clutch control member 52 provided with upturned fork elements inghandle-53. 0n= the-lower face of the threaded sleeve 32 is mounted f a pin 54 which .-is. arranged to engage the side face 52b of the-clutch "control element 52 whenthe' sleeve. 32 has attained its right-hand position onrthe splndle 3|.':rWhen the pin 54 engag'esthe clutch control block -52,

it moves the entire 'shaftjn to the right,-thus disengaging the two halves '46 and 41:'..of the clutch 45 and stopping the motion-of the apparatus. Onthe right-hand end ofnthespindle 3| is arranged a hand wheel 55-for resetting the apparatus. When the apparatus is returned to its starting position,-the clutch is automatically engaged and-the action of the'movable bar I6 begins again. The manual clutch control handle 53 provides means for disengaging the clutch 45 at any desired-moment, without waiting for the automatic disengagement totake place.

When controlling thestructure'of the yarn in i the second way described above, namely by increasing the speed of -rotationt of the spinning pot I!) as the spinning progresses the apparatus shown diagrammatically" at the bottom of- Fig. 2 may be employed for the purpose. spindle (shown partly broken away).1upon which the spinning pot I9: is mounted. I Itis arranged to be driven by means of an electric motor, 51

' which is supplied with current from a suitable for thegodet wheels; l1." -If .theseareall elec-' trically driven, their-speed; maybe controlled, if desired, by a rheostat (notshown, but similar to 59-60) which varies all of..their-'-speeds simultaneously, in such a waythat properrcoordination of the apparatus is maintained.

Apparatus for controlling the'structure of the yarn in the third way described above, namely by increasing-the. timethat the yarn is immersed in the spinning bath, is shown-in detailinFig. 9. In this apparatus-the movable bar I6 is arranged to travel from right to left,--as,,indicated by the ,arrow, instead of travellin irom left toright as shown, in the preceding ilgiirr-gs, Tothis end, the mechanism. for ,moving the bar, which is shown in detail, in Figs.. ,4 todinclusive described above, is mounted-at ,the left hand'endof the bar l6 instead rof at .the right,.as in Fig. 1, and

draws the bar to the left instead.of towards the In this arrangement-of apparatus, also, the

jfi xed or sickle guides -|4, are dispensed with and the yarn filaments l3; are. .carried].directly from the spinnerette: |2 :,to ,the movablelguide IS, the initial position of which isshown byf the full lines. During the progress of spinning "eachyarn cake the bar "5 moves tottheflleft in'suehawaythat theguide l5 is, carried Ifro'n' itfs initial pos'itio -i, shown by the full lines tothe position shown by the dotted lines'at 5'. The yarn filaments being moved from their initial'.position," 3; to the po.. sition shown by the dotted lines, at: I321: the distance that-the yarn v i'l larnents''travel through the liquid .of the spinning. bath" |0 'jaf ter ejecti n from the spinnere'tte [2f correspondingly increased, as shown in"the"drawi gs I h slew parat. arl'yingput the process of the invention y simultaneously and progressively increasing the tension applied :56 is the movable bar i6 is, in

,toleft as indicated by position is shown and then under time of Y characterized by the fact to the thread and increasing the time of it immersion in the spinning bath. In this arrange-- ment 'the sickle guide H is fixed, as in Fig. 3, but is placed above the movable bar i6 and movable guides I5.- The direction of motion of the 4 this case also, from right the arrow. The initial in full lines and the final position of the guide I5 is shown by the dottedlines at IS. The yarn filaments it are threaded first around the left side of the movable guide I! and around the right side of the fixed guide;l4, as shown. During the motion of the movable guide I! from its'initial position Hlto its final position, li'fifzthe tension on theyarn l3 isincreased by drawing'the yarn into the position shown-,hy'thedotted lines, and the immerjsionp 'the =.yarn5in the spinning 'structure'by a simultaneous application of the first and third 'methods described above;

The methods, and arrangements of apparatus, herein specifically illustrated and described are. the best now known to me, but it is to be understood that the invention is not necessarily limitedtc-the methods and constructions herein specifically illust-.ated,,but may be carried out in other ways without departing from its spirit.

I claim:

v 1. In the-manufacture of rayon by the centrifugal spinning process,'the method of producing yarn having substantially uniform dyeing qualities throughout all parts of the spun yarn cake which comprises ejecting viscose to be spun from a spinnerette-into a spinningbath, leading the viscose filaments'over guides to a centrifugal spinning pot, spinning the filaments by rotation of saidpot, and controlling the internal structure of the yarn filaments during the spinning operatlon by progressively introducing a correcting structural change in the filaments to compensate for variations of structure which would otherwise cause non-uniformity in the dyeing quality of the yarn in different parts of the yarn cake.

2. Method of spinning rayon yarn of substantlally uniform dye afllnity, wherein viscose is ejected from a spinnerette into a spinning bath, led over guides to a centrifugal spinning pot, and there spun into a yarn cake which builds from the wall of the pot inwardly towards its axis, that at least one of said operations is progressively adjusted-during the spinning of eac h yarn cake to compensate for structural variations in the yarn from outslde to inside of the cake, which variations wouldotherwise produce" yarn having a non-uniform dye affinity, said adjustment being coordinated wlththe other operations to produce a y'arn'cake' whereof the yarn; in all parts of the cake has substantially uniform dye amnity. 3. Method of manufacturing rayon yarn of substantially uniform dye affinity, which includes the steps of ejecting viscose into and passing it through a coagulating spinning bath, then passing it over guides to a centrifugal spinning pot, and there spinning it into yarn in a cake by the rotation and centrifugal actionof said-spinning pot, and progressively regulating at least one of said operations during the spinning of each yarn cake to compensate for characteristics of the yarn which would otherwise cause differences in the dye ailinity of the yarn in different parts of the spun cake. I

4. Method of spinning artificial silk thread sion applied to'the yarn.

to compensate for the reduction which comprises a i a prising spinnlngthe thread into a calI'e-accord- 5 the thread in different parts of the sunrise ingquality of l the thread in different parts of the cake.

5. In the manufacture of rayon by the centrifugal spinning process, the method of-producing yarn having substantially uniform dyeing qualities throughout all parts of the spun yarn cake which comprises progressively increasing during the spinning of each yarn cake,

in tension on the yarn caused by diminishing centrifugal pull upontheyarnasthe cakeisspun. isgailsofincreasediithusiaccomplishing pro- 'g'ressive. regulation of the yarn 6. In the manufacture of rayon by the centrifugal spinning process, the method of producing yarn having substantially uniform dyeing qualities throughout all parts of the spun yarn cake progressively increasing the speed of rotation of the spinning pct during the spinning of each, yarn cake to compensate for decreasing tension which would otherwise be applied to the yarn because of diminishing centrifugal pull upon the yarn as the cake is spun.

7. In the manufacture of rayon by the centrifuga'l spinning process, the method of producingyarn having substantially uniform dyeing qualitiesthroughout all parts of the spun yarn cake which comprises progressively increasing the speed of rotation of the spinning pot during the spinning of each yarn cake to compensate for deplied to the yarn because of diminishing centrifugal pull upon the yarn as the cake is spun, and simultaneously adjusting the speeds of the other parts of the spinning apparatus to maintain the the ten--' I creasing tension which would otherwise be ap- 9. Method of spinning artificial silk thread substantially uniform dye afllnit coming to the centrifugal spinning pot process and simultaneously effecting adjustment, of the during the spinning of the cake, to compensate otherwise cause non-uniform dyeing quality of cake.

10. Apparatus for the manufacture of artificial silk yarn having a substantially uniform dye affinity throughout the yarn cake comprising, in

'thread tension and adjustment of the time of immersion in the coagulating bath, progressively combination, a spinnerette for ejecting viscose filaments into a coagulating bath, a guide for leading the coagulated filaments to a godet wheel, a godet' wheel, a centrifugal spinning bucket for spinning the yarn into a cake, and automatically adjustable mechanical means associated with the foregoing apparatus for producing a progressive increase .in the tension applied to the yarn during the spinning of each yarn cake to introduce a correcting structural change in the yarn during the spinning of the cake, to compensate the variation in structure which would otherwise occur and cause non-uniformity in the dyeing quality of yarn from different parts of the same yarn cake.

11'. Apparatus for the manufacture of artificial silk yarn comprising, in combination, a spinnerette for ejecting viscose filaments into a coagulating bath, a guide for leading the coagulated filaments to a godet wheel, a godet wheel,

a centrifugal spinning bucket for spinning the yarn into a cake, and means for progressively increasing the tension applied to the yarn in the course of spinning a yarn cake to compensate for decrease in tension on the yarn due to decreasing centrifugal force as the cake is spun.

12. Apparatus for spinning artificial silk having a substantially uniform dye index, according to the centrifugal spinning bucket method, including automatically adjustable mechanical means comprising a movable tensioning device arranged to apply a progressively increasing tension to the yarn during the spinning of each yarn cake for producing a progressive structural change in the yarn, during the spinning of the cake to compensate the variation in structure which would otherwise occur and cause non-uniformity in the dyeing quality of yarn from different parts of the same yarn cake.

13. Apparatus for spinning artificial silk according to the centrifugal spinning bucket method, including means for progressively increasing the tension applied to the yarn 'in the course of spinning a yarn cake.to compensate for decrease in tension on the yarn due to the decreasing centrifugal force as the cake is spun.

14. Apparatus for spinning artificial silk according to the centrifugal spinning bucket method, including means for progressively and simultaneously increasing thetension applied to the yarn and the length of time that the yarn is immersed in the coagulating bath, during the course of spinning a yarn cake, to compensate for varying dye aflinity of the yarn which would otherwise occur in different parts of the yarn cake.

15. In the manufacture of rayon by the centrifugal spinning process, the method of producing yarn having improved uniformity of dyeing qualities which comprises ejecting a cellulosic solution from a splnnerette into a spinning bath,

-leading the resulting filaments over guides to a centrifugal spinning pot, spinning the filaments by rotation of said pot, and controlling the ina yarn cake, and means for progressively increasing the speed of at least one of said rotating elements to overcome the detrimental effect that decreased centrifugal force would otherwise have upon the dyeing properties of the yarn.

17. Apparatus for spinning, according ,to thehaving improved uniformity of dyeing properties,

comprising, in combination, a spinnerette for ejection of artificial silk filaments, a spinning bath for coagulating the filaments, a rotating godet roll for the filaments, a rotating centrifugal spinning bucket for spinning the filaments into a yarn cake, and 'means for progressively varying the speed of at least one of said rotating elements, while spinning each yarn cake, to produce a yarn cake in which yarn from all parts of the cake can be dyed with substantial uniformity.

18. In the manufacture of rayon yarn by the centrifugal spinning process, the method of producing yarn having improved uniformity of dyeing qualities, which comprises ejecting a cellulosic solution from a spinnerette into a spinning bath, leading the resulting filaments over a godet wheel to a centrifugal spinning pot, spinning and collecting the filaments into a yarn cake in said not by rotation of the pot, and progressively increasing a component of tension applied to the moving filaments during the collection of the yarn cake in said pot, to offset effects which would otherwise arise from decreasing internal diameter of the cake of collected filaments in the spinning pot during formation of the yarn cake, whereby the dyeing-quality of the yarn in different parts of the yarn cake is rendered more nearly uniform.

19. In the manufacture of rayon by the centrifugal spinning process, the method of producing yarn of improved uniformity, which comprises ejecting a cellulosic solution froma spinnerette into a spinning bath, leading the resulting filaments over a godet wheel to a spinning pot and collecting the filaments therein, and, during the travel of the filaments from the spinnerette to the pot, applying tension to the filaments and causing said tension progressively to increase as. the internal diameter of the package of collected filaments decreases, to offset variations which would otherwise cause non-uniformity of the collected yarn.

20. Apparatus for spinning artificial silk having improved uniformity of dyeing properties, comprising, in combination, a filament-ejecting spinnerette, a bath for coagulating the ejected filaments, a rotating collector for the filaments, and means for progressively increasing the tension on the filaments prior to their introduction into the collector, as the internal diameter of the collected package of filaments decreases, to overcome detrimental efiects which such decreasing internal diameter of the collected package of filamerits would otherwise have upon the dyeing properties of the silk.

21. In the manufacture of rayon by the centrifugal spinning bucket method, the process of producing artificial silk haying improved uniformity of dyeing properties, comprising, in combination,

the steps of ejecting artificial silk from a spinnerette, passing the ejected filaments through a spinning bath, passing the filaments over a rotating godet roll and into a rotating centrifugal spinning bucket, spinning the filaments into a yarn cake in said centrifugal bucket, and progressively varying the speed of at least one of said rotating elements, to overcome the detrimental effect that decreased centrifugal force would otherwise have upon the dyeing properties of the am. y FRANK WILFRED MATTINSON. 

